1. Field of the Invention
The present invention relates to a defect compensation method and a defect compensation apparatus for a liquid crystal display apparatus for irradiating a defective pixel with a laser beam to correct a light transmittance etc. and to thereby prevent the defective pixel from standing out.
2. Description of the Related Art
The various types of liquid crystal display apparatuses (liquid crystal panels) used for rear projection and front projection displays have as many as several hundreds of thousands to several millions of pixels arranged on the same panel. They are therefore particularly prone to element defects or wiring pattern defects in the switching elements (for example, thin film transistors or metal insulator metal (HIM) diodes) of the pixels. These appear as defects on the screen and lower the quality of the product yield.
As a countermeasure in this case, in for example an active matrix type liquid crystal display (LCD), use was made of a redundant circuit type of trimming method, where a plurality of switching elements were arranged in advance for every pixel and a switching element suffering from a malfunction and causing a pixel to be defective was separated by irradiation of a laser beam to restore the product.
In this redundant circuit type of trimming method, however, excessive switching elements and redundant wiring for irradiating the laser beam for separating them became necessary, so there was the problem that the pixel area was increased and a high degree of integration could not be achieved.
Further, the defective pixels sometimes could not all be restored depending on the size, position, and number of the defects.
For example, where the defect is caused by a particle of dirt, if the particle is large, sometimes it is scattered by the irradiation of the laser beam and creates a large stain-like defective region on the screen. Further, if all of the switching elements for a pixel malfunction, restoration was no longer possible. Further, there were cases where pixels could not be restored by separation of the defective switching element due to the position of the defect.